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From: Junglist on 18 Mar 2010 09:09
Hello!

I have read article "Optimum Masking Levels and Coefficient Sparseness for
Hilbert Transformers and Half-Band Filters Designed Using the
Frequency-Response Masking Technique", Yong Ching Lim, NOVEMBER 2005.

There're in example two filters Hb(z) and H1(z). I guess they derived by
multiplication classical hilbert impulse function h(n)=[1-cos(Pi*n)]/Pi*n
on different windows. What kind of windows is using there?
Thanks for any help.

Best regards,
Vasily


From: Rune Allnor on 18 Mar 2010 09:56
On 18 Mar, 14:09, "Junglist" <vasily.karpenko(a)n_o_s_p_a_m.gmail.com>
wrote:
> Hello!
>
> I have read article "Optimum Masking Levels and Coefficient Sparseness for
> Hilbert Transformers and Half-Band Filters Designed Using the
> Frequency-Response Masking Technique", Yong Ching Lim, NOVEMBER 2005.
>
> There're in example two filters Hb(z) and H1(z). I guess they derived by
> multiplication classical hilbert impulse function h(n)=[1-cos(Pi*n)]/Pi*n
> on different windows. What kind of windows is using there?
> Thanks for any help.

I don't have access to that particular IEEE journal, but
browsing some of the author's other articles that I do
have access to, it seems one key paper to look for
is reference [1],

Y. C. Lim, "Frequency-response masking approach for the
synthesis of sharp linear phase digital filter", IEEE Trans.
Circuits Syst., vol. CAS-33, no. 4, pp. 1986 .

Don't be surprised if you find the answer in that article.

Rune
From: dbd on 18 Mar 2010 11:52
On Mar 18, 6:09 am, "Junglist" <vasily.karpenko(a)n_o_s_p_a_m.gmail.com>
wrote:
> Hello!
>
> I have read article "Optimum Masking Levels and Coefficient Sparseness for
> Hilbert Transformers and Half-Band Filters Designed Using the
> Frequency-Response Masking Technique", Yong Ching Lim, NOVEMBER 2005.
>
> There're in example two filters Hb(z) and H1(z). I guess they derived by
> multiplication classical hilbert impulse function h(n)=[1-cos(Pi*n)]/Pi*n
> on different windows. What kind of windows is using there?
> Thanks for any help.
>
> Best regards,
> Vasily

Why do you suggest the use of windows here? The frequency response
masking literature takes advantage of a variety of filter design
methods, but usually optimizing techniques.

The original reference is:
Optimum masking levels and coefficient sparseness for Hilbert
transformers and half-band filters designed using the frequency-
response masking technique
Yong Ching Lim ; Ya Jun Yu ; Saramaki, T. ;
Sch. of Electr. & Electron. Eng., Nanyang Technol. Univ., Singapore
Circuits and Systems I: Regular Papers, IEEE Transactions on
Nov. 2005, Vol. 52 , Issue:11, page(s): 2444 - 2453

and the correct info for Rune's reference is:
Y. C. Lim, "Frequency-response masking approach for the synthesis of
sharp linear phase digital filter", IEEE Trans. Circuits Syst., vol.
CAS-33, no. 4, pp. 357, 1986
(it was incomplete on the IEEE site)

Dale B. Dalrymple
From: Clay on 18 Mar 2010 15:28
On Mar 18, 9:09 am, "Junglist" <vasily.karpenko(a)n_o_s_p_a_m.gmail.com>
wrote:
> Hello!
>
> I have read article "Optimum Masking Levels and Coefficient Sparseness for
> Hilbert Transformers and Half-Band Filters Designed Using the
> Frequency-Response Masking Technique", Yong Ching Lim, NOVEMBER 2005.
>
> There're in example two filters Hb(z) and H1(z). I guess they derived by
> multiplication classical hilbert impulse function h(n)=[1-cos(Pi*n)]/Pi*n
> on different windows. What kind of windows is using there?
> Thanks for any help.
>
> Best regards,
> Vasily

Perhaps this paper will shed some light for you:

http://www.ece.umassd.edu/Faculty/acosta/ICASSP/ICASSP_1996/pdf/ic961272.pdf

IHTH,
Clay



From: robert bristow-johnson on 18 Mar 2010 18:23
On Mar 18, 11:52 am, dbd <d...(a)ieee.org> wrote:
> On Mar 18, 6:09 am, "Junglist" <vasily.karpenko(a)n_o_s_p_a_m.gmail.com>
> wrote:
>
> > Hello!
>
> > I have read article "Optimum Masking Levels and Coefficient Sparseness for
> > Hilbert Transformers and Half-Band Filters Designed Using the
> > Frequency-Response Masking Technique", Yong Ching Lim, NOVEMBER 2005.
>
> > There're in example two filters Hb(z) and H1(z). I guess they derived by
> > multiplication classical hilbert impulse function h(n)=[1-cos(Pi*n)]/Pi*n
> > on different windows. What kind of windows is using there?
...
> Why do you suggest the use of windows here? The frequency response
> masking literature takes advantage of a variety of filter design
> methods, but usually optimizing techniques.

an implied window can come from any design technique as long as you
can avoid dividing a non-zero numerator by a zero denominator.

because half-band symmetry let's us ditch the even-numbered taps, any
design that imposes half-band symmetry can have its (properly aligned)
impulse response divided by the ideal

h[n] = (1 - (-1)^n)/(pi*n) (h[0]=0)

for odd n, and you have an implied window.

r b-j
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